The principal objective of the proposed program is to obtain an understanding, at a molecular level, of the effects of ultraviolet radiation on the ability of living organisms to synthesize proteins and nucleic acid molecules. The development of such an understanding will be achieved by determining the effects of ultraviolet radiation on the chemical compositions and physiological properties of nucleic acid and protein components of the cellular machinery for nucleic acid and protein synthesis; and elucidation of possible cellular mechanisms for reversal of these effects. BIBLIOGRAPHIC REFERENCES: Gorelic, L. (1976), Biochem., 15, 3579: "Photoinduced Crosslinkage in situ of 30 S Ribosomal Proteins to 16S rRNA - Identification of Crosslinked Proteins and Relationships Between Reactivity and Ribosome Structure." Gorelic, L. (1977), "Photoinduced Nucleic Acid-Protein Crosslinkage in Ribosomes and Ribosome Complexes," in "Symposium on Biochemical Consequences of Protein Crosslinks", published by Plenum Press, in press.